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Future wiring Scientists have made a strong, lightweight wire from carbon that might eventually be a rival to copper if its ability to conduct electricity can be improved.

The researchers, from Cambridge University, say it is the first time that the super-strong carbon wires, spun in a tiny furnace that looks like a candy floss machine with temperatures above 1000°C, had been made "in a usable form" one millimetre thick.

Krzysztof Koziol of the university's department of materials science and metallurgy says commercial applications were still years away but that "our target is to beat copper".

Wire made in the laboratory from carbon nanotubes (CNTs) -- microscopic hollow cylinders composed of carbon atoms -- is 10 times lighter than copper and 30 times stronger.

Among advances, the scientists found a way to solder CNTs to metal, something that had previously not been possible.

A big drawback for CNTs is that one kilogram of copper is 2.5 times more conductive than a kilogram of CNT.

For the next few years, Cambridge University researchers will focus on copper and CNT hybrids, a program to create "ultra-conductive" copper that is supported by the copper industry. In some blends, tiny amounts of carbon improve copper's conductivity.

The International Copper Association, representing producers of more than half the world's copper, says that mass production of ultra-conductive copper could be 10 years away if the science can be improved.

But development of pure high-conductive CNT carbon that could supplant the metal in wiring is a remote prospect, says Malcolm Burwell, the Association's director of technology in North America.

"It's a long way off. The industry doesn't stay awake at night worrying" about carbon nanotubes supplanting copper, he says. He adds that 60 per cent of all copper sold worldwide is used to carry electricity.

Carbon flexibility

Koziol, however, says pure CNT wires could have more immediate uses because they are more flexible than copper. That could be valuable in moving parts such as robot arms or in planes or cars where flexibility is more important than conductivity.

Weight can be crucial. About a third of the weight of a large space satellite, weighing 15 tonnes, is typically copper. According to the researchers, a Boeing 747 jumbo jet uses as much as 215 kilometres of copper wiring, weighing more than 2 tonnes.

The UK National Grid says a benefit of CNTs, if developed at commercial scale at a competitive cost, was that they can operate at high temperatures.

"A potential application ... is the ability to produce a conductor that operates effectively at high temperatures, reducing fatigue on our assets and extending the useful life of the conductor," says spokeswoman Gillian West.

"CNT may also be beneficial as it is lightweight and so much easier to transport to our sites," she says.